A photosensitive resin composition generally comprises a photosensitive resin and a photo-initiator. Capable of polymerization by irradiation with energy rays (light) to cure or be developed, a photosensitive resin composition finds application in photocurable ink, a presensitized printing plate, a photoresist of various kinds, a photocuring adhesive, and the like.
Photo-initiators are classified into photo-radical generators, photo-acid generators, and photo-base generators according to the active species generated on irradiation with energy rays (light). A photo-radical generator is advantageous in that a high curing rate is achieved and that the active species does not remain after cure but is disadvantageous in that oxygen can cause hindrance to cure so that any means for blocking oxygen, such as an oxygen-barrier layer, should be provided in forming cured film. A photo-acid generator has an advantage of insusceptibility to inhibition by oxygen but is disadvantageous in that a residual acid as an active species can corrode a metal substrate or denature a cured resin. A photo-base generator is attracting attention because of its less likelihood of suffering from such problems as hindrance by oxygen to cure and corrosion by a residual active species. However, the problem with a photo-base generator is low sensitivity (low curing performance) as compared with a photo-acid generator. Photo-base generators are disclosed, e.g., in patent documents 1 to 3 below.